Electric heater device

ABSTRACT

An electric heater device comprising a heater coil helically wound around an elongated insulated support member and incuding tensioning means for stretching the coil longitudinally of the support member to space adjacent coil loops one from the other. A pair of insulated members are provided over the faces of the support member to electrically insulate the coil and to press the helically wound coil loops toward the support member.

United States Patent [191 Erickson, deceased [111 3,821,517 [451 June 28, 1974 1 ELECTRIC HEATER DEVICE [75] Inventor: Ernest S. Erickson, deceased, late of New Castle County, Del. by Jane R.

Erickson, administratrix [73] Assigneez- Sperry Rand Corporation, New

York, NY.

[22] Filed: June 18, 1970 [2]] Appl. No.: 47,243

[52] US. Cl 219/546, 219/530, 219/542, 219/552, 338/297, 338/301 Int. Cl. 1105b 3/02 [58] Field of Search 219/345, 211, 528, 542, 219/544, 546, 530, 552, 553; 338/286, 296,

[56] References Cited UNITED STATES PATENTS 1,077,635 11/1913 Ovington 338/297 1,364,967 l/1921 Victor 338/301 X 1,767,716 6/1930 Stoekle 338/301 X 2,028,347 1/1936 Pelosi 219/211 X 2,153,152 4/1939 Mucher 338/301 X 2,398,892 4/1946 Kelly 338/301 X 2,544,547 3/1951 Vogel 219/546 X 2,761,042 8/1956 Scott 338/301 3,210,714 10/1965 Hummel r 338/301 3,556,705 l/1971 Mellett et all 338/299 X Primary ExaminerVolodymyr Y. Mayewsky Attorney, Agent, or Firm-Charles R. Miranda; Burtsell .1. Keams; Donald P. Walker 5 7] ABSTRACT An electric heater device comprising a heater coil helically wound around an elongated insulated support member and incuding tensioning means for stretching the coil longitudinally of the support member to space adjacent coil loops one from the other. A pair of insulated members are provided over the faces of the support member to electrically insulate the coil and to press the helically wound coil loops toward the support member.

4 Claims, 9 Drawing Figures ELECTRIC HEATER DEVICE BACKGROUND OF THE INVENTION The present invention is directed to new and useful improvements in heater devices for electrical appliances and in methods of making heater devices and more particularly to heater devices of the type wherein a coil of wire is wound around an insulated support member.

Certain portable electrical appliances such as electric hair curlers include a plurality of heat retaining hair rollers mounted on a heat sink surface such as a heat storing plate and which plate conducts heat to the rollers. Hair curler appliances of this type further include an electric heater device disposed adjacent the heat storing plate to conduct heat thereto. One such heater device comprises a coil of wire having loops that are tightly wound around an insulated support member. In devices of the latter type, individual tightly wound loops of the coil are fixed in spaced relationship along the length of the support member. If adjacent coil loops are not properly spaced on the support member one loop can touch another to effect a short circuit therebetween resulting in a lack of heat produced by the coil in the area where the loops are in contact.

In other wire-wound heater devices of this type the heater coil is wound about an insulated support mem ber, that is provided with serrations along a pair of parallel edges. Each individual loop of the heater element coil is tightly wound onto a respective serration such that the adjacent coil loops are spaced one from the other by the distance between serrations. In addition the surfaces of the serrations fix the spaced relationship of the loops on the support member to prevent short circuits therebetween.

In manufacturing and assembling the known types of wire-wound heater elements various problems and inconveniences are encountered. For instance the loops of these known heater elements are generally wound about the support member by hand or machine. Manual winding of the known devices is tedious, time consuming and consequently a costly operation. On the other hand, winding by machine requires relatively complex mechanical winding apparatus. As an altemative to winding the wire coil around a fixed support member a length of wire can be fed to a support member that is rotated as a mandrel such that the coil is formed thereon as the support member rotates. In this instance a special machine to hold and rotate the support member is required and which machine increases the cost of the final product to the consumer.

It is an object of the present invention to provide a novel electric heater device.

Another object is to provide a novel electric heater device wherein a resilient heater coil element is wound around an insulated support member and stretched along the length thereof to space the coil loops one from the other.

A further object is to provide a novel electric heater device wherein an insulated support member is disposed within a resilient wire-wound heater coil element and wherein tensioning means are provided at the ends of the element to stretch the coil longitudinally of the support member whereby adjacent coil loops are spaced one from the other.

A still further object is to provide a novel electric heater device wherein a resilient heater coil element is wound around an insulated support member and wherein cover strips are provided over the faces of the support member to electrically insulate the coil and to press the coil loops toward the support member.

Still another object is to provide a novel method for making an electric heater device.

BRIEF SUMMARY OF THE INVENTION The present invention contemplates a novel electric heater device. In one embodiment the heater device comprises an elongated insulated support member having a heater coil element helically wound thereon. Tensioning means are provided for stretching the heater coil element longitudinally of the support member whereby adjacent coil loops are maintained in a stretched and spaced condition. The electric heater device further includes a pair of insulated cover strips provided over the faces of the support member in close relationship therewith to electrically insulate the coil and to press the helically wound coil loops toward the support member.

The above and other objects and advantages of the present invention will appear more fully hereinafter from a consideration of the detailed description which follows taken together with the accompanying drawing wherein one embodiment of the present invention is illustrated.

DESCRIPTION OF THE DRAWING In the drawing:

FIG. I is a perspective view of an electric heater device which incorporates one embodiment of the present invention;

FIG. 2 is a front elevational view of the device of FIG.

FIG. 3 is a sectional view thereof taken on the line 3-3 of FIG. 2;

FIGS. 41, 5, 6, 7 and 8 respectively are views which show the steps of assembly of the electric heater dev1ce;

FIG. 9 is an enlarged fragmentary sectional view taken on the line 99 of FIG. 3.

DETAILED DESCRIPTION Referring now to the drawing for a more detailed description of the present invention an electric heater device incorporating an embodiment thereof is generally indicated by the reference numeral in FIG. ll.

Electric heater device 10 (FIGS. 1 and 2) comprises an elongated support member Ill and a heater coil element 12 (FIG. ll) having coil loops l3 helically wound about support member 11 in a manner to be described in detail. A pair of elongated rectangular shaped insulated cover strips 141 and 15 (FIGS. l and 2) are provided over support member 11 to cover loops 13.

Support member ill (FIGS. 1 and 3) is rectangular in shape and is formed of a heat resistant material such as silicon bonded mica paper. Member lll includes a pair of opposite and identical longitudinally extending support surfaces to support heater element 12, one of the support surfaces being shown at 16 in FIG. 1. Member 11 further includes a pair of longitudinally extending parallel side surfaces 117 one of which is shown in FIG. 1, which side surfaces are spaced apart by a distance designated W in FIG. 3, that represents the width of support member 11. Heater element 12 (FIG. 1) is made of a conducting material such as iron-chrome aluminum that is prewound in coil form prior to assembly of element 12 to support member 11. Coil loops 13 have a diameter designated D in FIG. 3 which diameter is of a larger dimension than the width W of support member 11. It is desirable that diameter D of loops 13 be larger than the width W of support member 11 to ensure that loops 13 are spaced from longitudinally extending side surfaces 17 (FIG. 3).

As mentioned it is a feature of the present invention to provide a heater element wherein adjacent coil loops 13 (FIG. 3) are spaced one from the other by tensioning means that stretch coil 12. To accomplish this a pair of fasteners such as eyelets 20 and 21 (FIG. 2) are provided at opposite ends 22 and 23 of coil 12 to secure coil 12 under tension to support member 11. Under this arrangement eyelets 20 and 21 maintain coil loops 13 in a stretched and spaced condition. A pair of terminal leads 24 and 25 (FIG. 1) are also secured to support member 11 by eyelets 20 and 21 respectively. Each lead 24, 25 includes a respective extension wire 26, 27 electrically interconnected to corresponding coil ends 22 and 23 (FIGS. 1 and 3).

Cover strips 14 and 15 (FIG. 2) are formed of an insulating material such as mica paper to electrically insulate coil 12 from other conducting surfaces. Cover strips 14 and 15 also serve to conduct heat away from coil 12. A pair of U-shaped recesses 28 and 29 are provided in cover strip 14 (FIGS. 1 to 3) adjacent terminal leads 24 and 25 to permit clearance for extension wires 26 and 27.

In assembling heater device 10 heater coil 12 is prewound in helical form (FIG. 4) with closely spaced coil loops 13. Support member 11 is then inserted through loops 13 of coil 12 (FIG. ),'or if desired coil 12 can be disposed around support member 11. Ends 22 and -23 of coil 12 are grasped and coil 12 is stretched for substantially the entire length of support member 11 (FIG. 6). After coil 12 has been stretched (FIG. 6) coil ends 22 and 23 and terminal leads 24 and 25 are secured to support member 11 by eyelets 20 and 21 respectively (FIG. I). In this manner coil 12 is secured under tension to support member 11 such that loops 13 (FIG. 6) are maintained ina stretched and spaced condition.

In accordance with this arrangement coil loops 13 (FIG. 6) extend above and below support surfaces 16 of support member 11. At this stage of assembly (FIG. 6) the spacing between adjacent coil loops 13 is governed by the distance between eyelets 20 and 21 (FIG. 6) and the unstretched length of coil 12 (FIG. 4). A desired ratio of eyelet distance to unstretched coil length is approximately I to 3 to provide adequate loop spacing prior to assembling cover strips 14 and 15 to support member 11. Cover strips 14 and 15 (FIG. 8) are fastened to support member 11 over support surfaces 16 by a pair of eyelets 30 and 31 (FIG. 2) and which cover strips tend to press coil loops 13 toward support member 11. The minimum distance between pressed coil loops on opposite support surfaces 16 of support member 12 (FIG. 2) is governed by the thickness of the support member. I

In use, heater element is disposed in an electric appliance with cover strip 14, for instance, placed in direct contact against a heat sink surface such as a heat storage plate (not shown) thereby permitting heat from coil 12 to be conducted through strip 14 to the heat storage plate. It will be appreciated that several heater devices 10 can be electrically connected at extension wires 26 and 27 in series or parallel arrangement depending upon the heat and power requirements of a particular appliance.

It will be apparent from the foregoing that an advantage of the novel heater device includes the use of a heater coil element which is prewound separately of the support member and which coil element has a loop diameter larger than the width of the support member. Under this arrangement the support member can be easily inserted into the coil instead of winding individual coil loops thereon. A further advantage among others is that the spacing between adjacent coil loops is achieved and maintained by stretching the coil and securing the coil under tension to the support member. In accordance with this arrangement there is no need to provide serrations, notches, or other spacing means on the support member or to tightly wind the coil around the support member in order to maintain adequate spacing between individual loops.

Although one embodiment of the present invention has been illustrated and described in detail it is to be expressly understood that the invention is not limited thereto. Various changes can be made in the design and arrangement of parts without departing from the spirit and scope of the invention as the same will now be understood by those skilled in the art.

What is claimed is:

1. An electric heater comprising:

a. an elongated insulated support member,

b. a pair of elongated cover members, one disposed on each side of the support member to sandwich the latter therebetween, said cover members being electrically insulative and heat conductive,

c. a stretched helical resilient resistance element having loops wound about the support member and being secured adjacent its ends to said support member, said ends being adapted for electrical connection to a source of energy and said loops having diameters of larger dimensions than the dimension of the support member, said resistance element extending longitudinally of the support member with the loops thereof being in contact with said cover members, and

(1. means securing together the cover members and said support member to compress said loops towards said support member while maintaining the loops spaced apart from each other, said loops of the resistance element between the support member and the cover members being in contact with the support member and said loops of the resistance element adjacent the longitudinal edges of the support member being spaced and out of contact with said longitudinal edges.

2. The electric heater of claim 1 wherein the support member and the cover members are of rectangular configuration.

3. The electric heater of claim 1 wherein the ends of the resistance element are fastened to the support member intermediate the points at which the support member and cover members are secured to each other.

said extension wires and said one cover strip. 

1. An electric heater comprising: a. an elongated insulated support member, b. a pair of elongated cover members, one disposed on each side of the support member to sandwich the latter therebetween, said cover members being electrically insulative and heat conductive, c. a stretched helical resilient resistance element having loops wound about the support member and being secured adjacent its ends to said support member, said ends being adapted for electrical connection to a source of energy and said loops having diameters of larger dimensions than the dimension of the support member, said resistance element extending longitudinally of the support member with the loops thereof being in contact with said cover members, and d. means securing together the cover members and said support member to compress said loops towards said support member while maintaining the loops spaced apart from each other, said loops of the resistance element between the support member and the cover members being in contact with the support member and said loops of the resistance element adjacent the longitudinal edges of the support member being spaced and out of contact with said longitudinal edges.
 2. The electric heater of claim 1 wherein the support member and the cover members are of rectangular configuration.
 3. The electric heater of claim 1 wherein the ends of the resistance element are fastened to the support member intermediate the points at which the support member and cover members are secured to each other.
 4. The electric heater of claim 3 wherein eyelets are used to fasten the ends of the resistance element to the support member and first and second extension wires are electrically connected to the ends of said element at said eyelets, and one of said cover members being provided with U-shaped recess portions in alignment with said extension wires to provide clearance between said extension wires and said one cover strip. 